Since we updated the devkit dependencies, we need to update
the browserslist DB versions in integration tests to avoid
browser mismatches causing errors like the following:
```
BrowserslistError: [BABEL] /tmp/ng-integration-test-91jP3g/test-sandbox/node_modules/zone.js/fesm2015/zone.js: Unknown version 114 of edge (While processing: "base$0$0")
```
PR Close#50772
Adds support for TypeScript 4.8 and resolves some issues that came up as a result of the update.
Most of the issues came from some changes in TypeScript where the `decorators` and `modifiers` properties were removed from most node types, and were combined into a single `modifiers` array. Since we need to continue supporting TS 4.6 and 4.7 until v15, I ended up creating a new `ngtsc/ts_compatibility` directory to make it easier to reuse the new backwards-compatible code.
PR Close#47038
Alan Agius